Abstract: Effect of strain age on impact toughness of δ=42 mm ADB610 steel was investigated by least square method,correlation coefficient test,K-S test,F test and t test.It can be concluded that the impact toughness of ADB610 steel through 5% strain age and non-strain-age obeys normal distribution,and there are indistinct difference in mean value and standard deviation of impact toughness of ADB610 steel between through 5% strain age and non-strain-age,that is the impact toughness of δ=42 mm ADB610 steel is insensitive to strain age within the range of 5% strain.